textproduct: Albany

WHAT HAS CHANGED

Winds are anticipated to remain elevated across much of the region through daybreak courtesy of steep height rises, persistent cold air advection, channeled and downsloped westerly flow, and deep mixing into a weakening, though still amplified, low- level jet. Therefore, we have maintained the Wind Advisory for most through 7 AM. That being said, we have also downgraded the previous High Wind Warning in the Taconics, Southern Greens, and Berkshires to the pre-existing Wind Advisory so these zones, too, will be under this headline through 7 AM. Maximum expected wind gusts through this time will range from about 45 to 55 mph.

Additionally, the probabilities for Advisory-Level snowfall (at least 4") have increased for Tuesday, December 23rd. While the highest probabilities for 4" of snow or greater remain confined primarily to the highest elevations of the Southwest Adirondack, non-zero probabilities have expanded across the region since the previous forecast issuance. Based on the latest guidance, snow could impact the morning and possibly the evening commutes and any holiday travel. Please see the discussion below (specifically, "Key Message 2" and its associated discussion) for additional details.

KEY MESSAGES

1. Largely dry conditions can be anticipated through the remainder of the weekend and into the beginning of the holiday week, though a couple of passing disturbances bring the potential for light upslope and lake effect snow showers Sunday and Monday.

2. Confidence is increasing in the potential for light to moderate, accumulating snowfall late Monday night through Tuesday which could impact both the morning and evening commutes as well as any pre-holiday travel.

3. Temperatures are trending above normal for Christmas and the weekend following with chances for rain increasing.

DISCUSSION

KEY MESSAGE 1... Surface high pressure continues to build north and eastward from the Ohio Valley beneath an upper-level ridge as yesterday's low departs farther to the north and east. Persistent cyclonic flow and cold air advection ahead of these features has maintained lake effect showers, primarily across the Southwest Adirondacks and Mohawk Valley, throughout the overnight thus far. However, with subsidence increasing across the region, latest scans of the KENX radar are already beginning to see a weakening trend in reflectivity, alluding to an end in the near future.

The surface anticyclone will drift farther eastward throughout the day today, reinforcing dry conditions across all of eastern New York and western New England with much slower wind speeds than yesterday. Much more pleasant weather conditions will be met with chillier than yesterday, though more seasonable, high temperatures in the upper 20s to upper 30s.

For the most part, dry conditions will remain in place through tonight and into Sunday. However, as today's high departs to the east tonight, a frontal system passing by to our north through Sunday will bring some light upslope and lake effect snow showers to portions of the Southwest Adirondacks, western Mohawk Valley, and Eastern Catskills. Minor accumulations of a couple tenths to isolated amounts of 2 inches will result through Sunday before high pressure builds in once again to bring the return of regionwide tranquility. Lows tonight will fall widely to the 20s before Sunday's highs reach the upper 20s to low 40s. Lows Sunday night will then fall to the single digits to low 20s behind the cold front of the aforementioned frontal system. Monday's highs will be in the 20s and 30s also as a result of this front.

KEY MESSAGE 2... While there continues to be some uncertainty, particularly surrounding timing and track, pertaining to a storm system anticipated for Tuesday, confidence is increasing in light to moderate, accumulating snow across the region.

General consensus currently indicates a low pressure system ejecting eastward from around the Upper-Midwest/South-Central Ontario. A leading warm front will increase warm advection and subsequent isentropic lift across the region, leading to an area of stratiform snow developing as early as Monday night. Snow, potentially mixing with rain in valley areas courtesy of warming temperatures in the wake of the warm front, continues throughout the day Tuesday as a series of shortwaves pulse through the mean upper- level flow and increase forcing for ascent. By late Tuesday evening, the low's trailing cold front rotates through eastern New York and western New England allowing precipitation to become limited primarily to the higher terrain in the form of snow through Tuesday night.

As of this forecast issuance, the 01z run of the NBM v4.3 has shown an overall increase in the probabilities for Advisory- Level (at least 4") snowfall across the region. That said, the highest probabilities for at least 4" of snowfall lie in the Southwest Adirondacks where values range from about 30-50%. Probabilities in the Eastern Catskills, Southern Greens, and Berkshires range from about 20-30% with valley areas only seeing about 10-20%. Based on these probabilities and the discrepancies in model depiction of this system, we currently have low to medium confidence in Advisory-Level snowfall Tuesday. However, with regionwide probabilities ranging from about 40-90% in at least 1" of snowfall, we have medium to high confidence in most areas seeing at least light accumulations of snowfall Tuesday. We will continue to monitor this situation closely, especially with it being so close to the Christmas Holiday and with latest guidance leaning towards snow falling during both the morning and evening commutes, to provide details on the anticipated travel impacts.

KEY MESSAGE 3... Dominant high pressure looks to ensure a dry Christmas Holiday on Thursday with temperatures looking to fall into the above- normal category. Latest NBM high temperature values range from the mid 30s to low 40s Christmas Day. Generally, this above- normal trend looks to continue into the Friday following Christmas with highs in the mid/upper 30s to possibly upper 40s in places! And, with conditions looking to be unsettled, rain looks to also be on the horizon before the New Year.

AVIATION /12Z SATURDAY THROUGH WEDNESDAY/

Through 12Z Sunday...Early MVFR cigs at PSF improve to VFR shortly after 12 UTC with VFR conditions at all terminals the remainder of the TAF period. Early clouds at ALB/PSF give way to clearing with mainly sunny skies at all terminals through early afternoon before high and mid clouds redevelop and lower this evening.

Westerly winds ranging 10-20kt with gusts of 20-30 kt early this morning before winds noticeably weaken by 15-16 UTC. Then, winds back to the S/SE this afternoon with sustained winds 5-10 kt and gusts to 15-25 kt this evening. LLWS concerns increase by 23-01 UTC and continue through 09-11 UTC for ALB, POU and PSF as the S/SW low-level jet above the sfc inversion strengthens to 35-55kt.

Outlook... Sunday Night: Low Operational Impact. Breezy. Slight Chance of SHSN. Monday: No Operational Impact. NO SIG WX. Monday Night: Moderate Operational Impact. Chance of SHSN. Tuesday: High Operational Impact. Definite SHRA...SHSN. Tuesday Night: Moderate Operational Impact. Chance of SHRA...SHSN. Wednesday: No Operational Impact. NO SIG WX. Wednesday Night: Low Operational Impact. Slight Chance of SHSN. Christmas Day: Moderate Operational Impact. Chance of SHRA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...Wind Advisory until 7 AM EST this morning for NYZ033-038>042- 047>054-058-061-063-082-083. MA...Wind Advisory until 7 AM EST this morning for MAZ001-025. VT...Wind Advisory until 7 AM EST this morning for VTZ013-014.